Aircraft, while parked, or when taxiing or being towed from one ground location to another, are subject to having their extremities, such as wingtips, collide with another object. Even in small private aircraft, the wings are long and the person moving the aircraft is not normally close to the wingtips, nor to the elevators or rudder, so it is difficult to judge their locations. It is therefore all too common to have collisions between the extremities of one aircraft and those of another on the ground. It is also common to have collisions for example between aircraft wingtips and the edges of hanger door openings or other objects in the hanger. The damage caused by these collisions is not always evident, but it is usually costly to repair and can render the aircraft non-airworthy.
Various attempts have been made to develop systems to avoid these collisions. For example, U.S. Pat. No. 6,963,293 to Rodger Rast shows an illumination system to reduce the number of collisions. Unfortunately, the system is complex and expensive.
U.S. Pat. No. 6,118,401 to Bruce Tognazzini shows another system in which detecting devices such as a radar or a video camera are mounted in the wingtips. Again, this is complex and expensive.